1. Field of the Invention
This invention relates to finned heat transfer and like surfaces, and particularly to methods of making and of attaching fin-like material to parent surfaces. A parent surface may have fin-like material attached thereto for reinforcement and other purposes. For disclosure purposes, however, the invention will be considered as dealing with problems of providing extended surface fins to a heat transfer surface, especially a curved heat transfer surface.
2. Description of the Prior Art
A heat conductive part separating flowing fluids of different temperature will sometimes be provided with fins which extend outwardly into the flow path of either one or both fluids. The fins improve heat transfer efficiency. Where the thickness and machinability of the part permits, a surface thereof can be milled with multiple, parallel slots to form the desired fins. This is a relatively expensive operation, and, as indicated, is unavailable when the part is made of a relatively thin sheet metal or the like. In another method, a strip of a fin material is superimposed on and brazed to the heat transfer surface, the strip being an accordion-like part comprised of multiple connected corrugations. Since fluid flow cannot conveniently take place transversely of the corrugations, the strip is oriented so that fluid flow occurs longitudinally of or lengthwise of the strip. Although this method produces a finned heat transfer surface it may be undesirable as imposing an excessive pressure drop, or as adding excess weight. It has, in any event, a specific disadvantage in that the strip cannot be bent to conform to a surface curved in the direction of fluid flow. That is, a corrugated fin strip is readily flexible and easily bent about an axis parallel to the corrugations but is essentially rigid as against, and strongly resistant to, bending forces applied in a transverse sense.